Big Lake vs Grace Lake
Water quality, depth, fish species, and recreation comparison.
Big Lake reads lower on nutrients and algae than Grace Lake. Both are in Beltrami County, Minnesota.
Big Lake and Grace Lake are both in Minnesota — a same-state head-to-head where the comparison comes down to lake-specific differences in depth, watershed, and monitoring history rather than the broader state-level water-quality regime. Big Lake reads materially cleaner than Grace Lake on nutrients and algae. A gap that wide is unlikely to close in a single year of remediation work; it reflects multi-decade differences in the lakes themselves.
For a recreational visitor, the wider gap in the readings is decisive: Big Lake has the lower nutrient and algae numbers. For a researcher, the gap is the interesting part: what is different about the two watersheds, and which of those differences is mutable?
Big Lake
Moderate clarity, visible to about 9.7 ft.
Grace Lake
Crystal clear, you can see 15 ft down.
Side-by-Side Metrics
| Metric | Big Lake | Grace Lake |
|---|---|---|
| Water Clarity | 9.7 ft | 15 ft Better |
| Phosphorus | 15 µg/L Better | 21.5 µg/L |
| Chlorophyll-a (Algae) | 4.8 µg/L Better | 9.3 µg/L |
| Maximum Depth | 35 ft | 42 ft Better |
| Surface Area | 3,598 acres | 860 acres |
| Public Access | Yes | Yes |
| Fish Species | 17 Better | 13 |
| Trophic State | mesotrophic | mesotrophic |
A green ✓ marks the better value for that metric (lower phosphorus / chlorophyll = cleaner; higher Secchi / depth / species count = better). Surface area and trophic state carry no tick — a bigger lake is not a better lake.
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Verdict
Big Lake reads lower on nutrients and algae than Grace Lake. Water clarity: 9.7 ft vs 15 ft. For fishing diversity, Big Lake also leads with 17 species.
Source: EPA National Aquatic Resource Surveys, 2026.